ep1sgx25d Altera Corporation, ep1sgx25d Datasheet - Page 72

• Manufacturer Part Number: ep1sgx25d
• Description: Stratix Gx Device Family Data Sheet
• Manufacturer: Altera Corporation

Logic Elements
Figure 4–5. LE in Normal Mode
Note to
(1)
4–6
Stratix GX Device Handbook, Volume 1
This signal is only allowed in normal mode if the LE is at the end of an adder/subtractor chain.
Figure
addnsub (LAB Wide)
data1
data2
data3
cin (from cout
of previous LE)
data4
4–5:
(1)
clock enable control for the register. These LAB-wide signals are available
in all LE modes. The addnsub control signal is allowed in arithmetic
mode.
The Quartus II software, in conjunction with parameterized functions
such as library of parameterized modules (LPM) functions, automatically
chooses the appropriate mode for common functions such as counters,
adders, subtractors, and arithmetic functions. If required, you can also
create special-purpose functions that specify which LE operating mode to
use for optimal performance.
Normal Mode
The normal mode is suitable for general logic applications and
combinatorial functions. In normal mode, four data inputs from the LAB
local interconnect are inputs to a four-input LUT (see
Quartus II Compiler automatically selects the carry-in or the data3
signal as one of the inputs to the LUT. Each LE can use LUT chain
connections to drive its combinatorial output directly to the next LE in the
LAB. Asynchronous load data for the register comes from the data3
input of the LE. LEs in normal mode support packed registers.
Register Feedback
4-Input
LUT
Register chain
connection
clock (LAB Wide)
(LAB Wide)
ena (LAB Wide)
aclr (LAB Wide)
sload
(LAB Wide)
sclear
(LAB Wide)
ADATA
ENA
D
ALD/PRE
aload
CLRN
Q
Row, column, and
direct link routing
Row, column, and
direct link routing
Local routing
LUT chain
connection
Register
chain output
Figure
Altera Corporation
February 2005
4–5). The